steve walker

well the 66 425 has a knock when givin gas it misfires and knocks using a stethoscope it sounds from front of mtr both sides and front top of valve covers and fuel pump. at idle nothing . changed oil,cap rotor,everything else is old.so any thoughts

oldcutlass

Disconnect all the belts, if the noise is still there, it may be time to take it apart.

droldsmorland

Misfire, knock could be the dwell is way off...points ignition. Big difference in rod knock vs timing knock... hard to tell with out being there. Cam lobe, broken valve spring, bad valve or disaster in the lower end? Start simple with ignition settings. Read the plugs. Then dig deeper. Please follow up on what you find to complete the thread.

steve walker

wouldn't a rod knock be happening all the time ??

oldcutlass

It could be a lot of things, timing chain, rocker arms, lifters, bearings, wrist pins, cam,...

cjsdad

Not necessarily. I had a rod eat the crank out from under it once on a SBC and it was quiet until the RPMs hit 2100. I could reach 54 MPH so I drove it for a month that way 'till I could get a new/used crank. The bearing never spun in the rod but the crank was eaten away something awful, and only under that rod.

steve walker

man the gods have claimed her just shut off no noise she locked up cant get it too move by socket on harmonic bal took cover off real clean chain has sum slop and valvetrain looks real clean no smudge ...that sucks so what would make it lock up I can put a socket on cam and it will move .but on bottom and wah wah wont budge...

76olds

I had a bent rod in my 76 olds 350 and the knock was constant from start up to shut down, Jus sayin'

droldsmorland

Pull the plugs and try to turn it over. Carefully cut open the oil filter (removed from the engine) and see how much metal is in the filter media pleats. Then drain the oil and look for metal. If its truly cooked you will find metal. Time for a tear down. Have you looked at the plugs yet? If you sucked a valve the plug will usually look like it was struck with a sledge hammer.

Oldsmaniac

A spun bearing will lock up the crank.

Octania

A couple of 425's on CL near Lansing right now. One rebuilt for cheap.

I was going to suggest your knock was from varying timing due to slop in the distributor shaft until you related that it seized.

Rod bearing.

steve walker

well it looks like one of the front two .as when I pulled the pan there is a slight amount of metal flake in that area ill try too pull the bottom of both of too see but its still in car ..so ive put some stuff in4sale too help fund the rebuild of the 425 or a 455 .....

steve walker

well it was the no 1 rod bearing spun around and locked the mtr pulled rod cap apart and moves now.. sucks theres light scoring on the 1 and 2 rod on the crank others look nice and polished looks like it was cut 10 under as too the rod bearings....

Oldsmaniac

You will need to have the crank checked for straightness, and probable turning again and have all rod big ends checked for size.

Octania

pffft
get another crank and bearing kit
EASY FIX
MAW do a full teardown and flush the passages out.

steve walker

ahh already taking in a crank now to get turned

Oldsmaniac

If you dont have the rod big end trued you may be doing this again real soon.

steve walker

I wish I could but the side of the conn rod was damaged so Ive got spare 425 rods so they will be pressed out ill throw them in the freezer for days then use my press and press them out ...............just kidding place will do them for $5 a piece with a conn rod htr ......

steve walker

well started pulling mtr at 530 pm and at 830 pm mtr out felt this one was easy compared to my 455s maybe its cause ive pulled too many 455s

steve walker

yep ground down/ clean up the oil passages in main and frnt of mtr,and heads. also put epoxy down in lifter valley for ease of oil back to pan. sadly I found that prev a screw had came loose and went in mtr hit a piston and theres a small crack on top were that screw hit so I need a hi comp 425 piston stock bore ...don't think jb weld is going to fix that ..........

steve walker

sounds real good too. fires right up

Run to Rund

Which hi comp piston? Toro or 88-98?

steve walker

hi allready got it.. a toro hi comp one